Pau d’Arco bark comes from the Red Lapacho tree found in the long Andes of South America. It is harvested by peeling the inner bark in a vertical manner, starting from the ground going up until it reaches to the height of an adult man. Traditional history claimed its use for thousands of years. The first modern scientist to research the plant’s chemical composition was Dr. Theodore Meyer from the National University of Tucuman, Argentina. He discovered that Pau d’Arco contains xyloidin – a compound with reputed antibacterial and viricidal activity. It also contains lapachol, a substance noted for its anti-cancer properties.
The inner bark referred to as the as cortex of the Pau d’Arco tree functions as the primary water and food storage medium and eventually turns into outer bark as the tree matures. The cortex, which serves as the medicinal part of the plant, may range in color depending on the type of Pau d’Arco specie, from deep red brown to plain brown to pinkish brown with sections of straw-like shades and charcoal gray. The general appearance varies in relation to the wood and the age, species and environmental factors unique to the place of harvest.
The preference of native adherents for the inner bark instead of the outer bark seems to be widespread. For instance, in the northwestern coast of Canada, the Salish Indians strongly believed that the true medicinal portion of the tree was found in its cortex, which they deemed as the softer, lighter and moister inner section of the bark.
The medicinal use of Pau d’Arco can be traced back to several centuries in the past, with native tribes of South America and the Incas using the bark externally as a poultice or internally through decoction by treating various types of skin diseases such as psoriasis, fungal infection, eczema, hemorrhoids and skin cancer. The tea derived from the bark is also considered a blood purifier, a treatment for ulcer, rheumatism and even a cure for leukemia. It is also used as a febrifuge and a diuretic.
The growing popularity of Pau d’Arco bark in Western medicine is credited to the plant’s antifungal property for the treatment of system yeast infection, more notably the growth of Candida albicans. Yeast infections usually followed by antibiotic therapy can be resistant to modern therapeutic management. However, with the antifungal activity of Pau d’Arco, the plant’s compounds may be used to combat this microorganism by the affected patient taking three glasses of Pau d’Arco tea per day. Besides its notable anti-fungal activity, it also contains astringent substances that can shrink inflamed tissues. It also has bitter compounds that aid proper digestion and anti-tumor activity in certain forms of skin and blood type cancers. On top of its medicinal properties, it is a good herbal source of essential nutrients including calcium, cobalt, silicon and crude fiber.
Pau d’Arco bark is traditionally used in different parts of South America. In Costa Rica, the bark decoction is used to treat colds, flu, fever, headache and constipation. In Panama, the bark is topically applied to cure boils and wounds and as fungicide. In Guatemala, the bark is given to dogs as a protection from rabies. In Colombia, the bark tea is gargled to treat sore throat and other throat diseases.